1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a liquid crystal display device and a substrate therefor.
2. Discussion of the Related Art
Until recently, display devices have typically used cathode-ray tubes (CRTs). In recent years, many efforts have been made in studying and developing various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays (FED), and electro-luminescence displays (ELDs), as a substitute for CRTs. Of these types of flat panel displays, the LCD devices have several advantages, such as high resolution, light weight, thin profile, compact size, and low voltage power supply requirements.
In general, an LCD device includes two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other such that a voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into the direction of the induced electric field, thereby changing the light transmittance of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field.
The two substrates for the LCD device are referred to as an array substrate and a color filter substrate. The array substrate includes gate and data lines to define a sub-pixel region, a thin film transistor and a pixel electrode. The color filter substrate includes a black matrix, a color filter and a common electrode. To display color images, the color filter includes red, green and blue color filter segments corresponding to the respective sub-pixel regions. The three sub-pixels having the red, green and blue define one pixel.
However, the LCD device using the three color filter segments has a low luminance. In other words, when a light emitted from a backlight passes through the color filter, the passed light has a luminance of 33 percent with respect to a luminance of the emitted light.
Accordingly, the LCD device further uses a white color filter segment (i.e., a transparent layer) to raise a luminance thereof.
FIG. 1 is a schematic plan view of a color filter substrate for the LCD device having red, green, blue and white color filter segments according to the related art.
As shown in FIG. 1, the red, green, blue and white color filter segments “R”, “G”, “B” and “W” correspond to the respective sub-pixel regions, and are arranged regularly. The four color filter segments “R”, “G”, “B” and “W” define one pixel 100. In a non-pixel region between adjacent sub-pixel regions, where gate and data lines and a thin film transistor of an array substrate are disposed, a black matrix 10 is disposed.
Since the related art LCD device including the white color filter segment requires array components, such as gate and data lines, a thin film transistor and a pixel electrode, for the white sub-pixel. Accordingly, production processes and costs increase, and a design for the array substrate is difficult. Further, driving integrated chips (ICs) to drive the white sub-pixel is required, and thus incidental parts and production costs are required.